1. Field of the Invention
The present invention relates generally to a wafer cleaning apparatus used in a semiconductor manufacturing process, and more specifically to a wafer cleaning apparatus having features in sealing and box structure in the cleaning apparatus.
2. Related Arts
Recently, as integrated density of semiconductor devices is increased, wiring in circuits is made to be more micro-structured and also a distance between adjacent wires of wiring (hereafter referred to as wiring distance) is become narrower. Especially in a photo-lithography with a wiring distance less than 0.5 micrometer, a shorter focal depth of a stepper requires an imaging surface to be of fine flatness. In addition, since a trouble such as short-circuit of wiring may occur when there is a particle having a size longer than that of the wiring distance on a wafer, it is important in a wafer processing to keep a clean environment as well as to accomplish a required flatness. These requirements are also applied to a processing treatment of various wafers such as a glass substrate used for masking, a liquid crystal panel or the like. A cleaning apparatus has been used to clean the wafer, but a conventional wafer cleaning apparatus has problems described below.
Each component disposed in a cleaning chamber of the wafer cleaning apparatus for cleaning the wafer is generally made of material with superior corrosion resistance against cleaning chemical liquid or the like, such as synthetic resin or ceramics.
In a power section including a driving motor, an air cylinder or the like for driving said wafer or cleaning mechanism, however, some components are required to be made of metal due to a machining precision or a strength required therefor. In some cases, a surface treatment such as resin coating is applied to such metal components, but, in case of a sliding or a fitting portion, it is sometimes difficult to apply the surface treatment because of high precision required therefor. Therefore, it is important to separate the cleaning chamber from the power section by a reliable sealing method in order to prevent the metal portions from being exposed to an inside of the cleaning chamber so as for the power section to be protected from being brought into contact with the cleaning chemical liquid.
As for the sealing method, a gasket or an O-ring may be employed to seal a stationary portion. In an operative portion accompanied with a relative movement between components, a sealing member made of flexible resin material may be employed to shut off a leakage.
In the sealing member made of resin material, however, there is a possibility of the sealing property being damaged by cracking formed thereon due to an aging or a stress applied thereto by repeated motions.
In the sealing portions employing the gasket or the O-ring, there is also a considerable possibility that these components might be cut or nicked during repeated disassembling and assembling in maintenance services or the like resulting in a certain level of damage of the sealing property possibly causing an effusion of the cleaning liquid.
In view of the above-mentioned situation, the present invention has been made, and a primary object thereof is to provide a wafer cleaning apparatus capable of preventing a failure affecting all over the apparatus even if the sealing property of the sealing member is damaged.
In order to solve the problem described above, the present invention provides a wafer cleaning apparatus in which a cleaning chamber for cleaning a wafer by a cleaning means while rotating the wafer is separated by a partition member from a power section driving at least one member in the cleaning chamber, and a power of the power section is transmitted to the cleaning chamber by inserting a first member, i.e. a power transmission mechanism, connected to the power section into the cleaning chamber through an opening formed on the partition member.
The cleaning apparatus comprises further a dam in the opening of the partition member so as to surround the power transmission mechanism and to be protruded into the cleaning chamber so that a liquid entering into the opening is drained through a clearance between the opening and the dam to any place other than the power section, and a flexible sealing member mounted on a portion of the cleaning chamber surrounding the dam so as to seal the opening of the partition member.
Further, the present invention provides a wafer cleaning apparatus in which a sensor for detecting a leakage liquid from the cleaning chamber into a clearance between the sealing member and the dam is provided and thereby a leakage from the cleaning chamber is detected.
Further, the present invention provides a wafer cleaning apparatus in which the cleaning chamber for cleaning the wafer by the cleaning means while rotating the wafer is enclosed by a first box structure and said first box structure is enclosed by a second box structure so as to make a double-box structure.
Further, the present invention provides a wafer cleaning apparatus in which a pressure in the first box structure is kept to be lower than that in the second box structure. In order to accomplish this condition, for example, there is provided an exhaust equipment having a first exhaust hole opening to the first box structure, a second exhaust hole opening to the second box structure, and an exhaust pipe communicating with both of the first and the second exhaust holes so as to exhaust them through one exhaust pipe, wherein an exhaust resistance of the second exhaust hole is controlled to be higher than that of the first exhaust hole.
Further, the present invention provides a polishing apparatus comprising a polishing machine for polishing a wafer surface to be polished by bringing said wafer surface into contact with a polishing surface of a polishing tool and a cleaning machine for cleaning the wafer polished by the polishing machine, said polishing apparatus characterized by employing the wafer cleaning apparatus described above as the cleaning machine.